If you declare a uniform that isn't used anywhere in your GLSL code the compiler will silently remove the variable from the compiled version which is the cause for several frustrating errors; keep this in mind!

Shaders are also very isolated programs in that they're not allowed to communicate with each other; the only communication they have is via their inputs and outputs.

Shaders always begin with a version declaration, followed by a list of input and output variables, uniforms and its main function. Each shader's entry point is at its main function where we process any input variables and output the results in its output variables

GLSL types

GLSL Vector Container A vector in GLSL is a 1,2,3 or 4 component container for any of the basic types just mentioned. They can take the following form (n represents the number of components)

Components of a vector can be accessed via vec.xwhere x is the first component of the vector. You can use .x, .y, .z and .w to access their first, second, third and fourth component respectively. GLSL also allows you to use rgba for colors or stpq for texture coordinates, accessing the same components.

The vector datatype allows for some interesting and flexible component selection called swizzling. Swizzling allows for the following syntax:

We can also pass vectors as arguments to different vector constructor calls, reducing the number of arguments required:

ins and outs Shaders are nice little programs on their own, but they are part of a whole and for that reason we want to have inputs and outputs on the individual shaders so that we can move stuff around. GLSL defined the in and out keywords specifically for that purpose.

ins and outs 2 Each shader can specify inputs and outputs using those keywords and wherever an output variable matches with an input variable of the next shader stage they're passed along. The vertex and fragment shader differ a bit though

If we want to send data from one shader to the other we'd have to declare an output in the sending shader and a similar input in the receiving shader. When the types and the names are equal on both sides OpenGL will link those variables together and then it is possible to send data between shaders

Uniforms Uniforms are another way to pass data from our application on the CPU to the shaders on the GPU

To declare a uniform in GLSL we simply add the uniform keyword to a shader with a type and a name. From that point on we can use the newly declared uniform in the shader. Let's see if this time we can set the color of the triangle via a uniform

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Open-mindedness is a precondition for generating new ideas, but focusing on the problem is almost equally important.

The only thing worse than starting something and failing ... is not starting something.

We must speak our minds openly, debate our disagreements honestly, but always pursue solidarity.

If they would have told me when I was just 18 that I was going to have a career that would last so long, I'd have said it was impossible, that it was crazy that that could happen in my life, so I'm happy to be here. To be able to go out on stage every day.

When I moved to Brighton from London in 1995, I was struck by what I thought of as its townliness. A town, it seemed to me, was that perfect place to live, neither city nor country, both of which like to think they are light years apart but actually have a great deal in common.

Like when I'm singing live I can't hear myself. I'm just listening to the rest of the band. To listen to my voice, it doesn't even feel like it's me.

Everybody notices if you're the last one in in the morning and the first one to go in the evening. Always remember that as an employee.

It takes a while to realize that just because you're a stand-up comedian and you do comedy, you're not going to be good at all comedy.

Cantonese, which has up to nine tones as opposed to the five in Mandarin, is much more versatile and one of the richest dialects in Chinese.

I like to do things that are surprising and different.

Most modern calendars mar the sweet simplicity of our lives by reminding us that each day that passes is the anniversary of some perfectly uninteresting event.

If you can write DNA, you're no longer limited to 'what is' but to what you could make.

I'll always have a house in London; I'll always call it my home. There might be moments when I get to go and work in different parts of the world, but I'll always come back here.

Therefore, since we are surrounded by such a great cloud of witnesses, let us throw off everything that hinders and the sin that so easily entangles. And let us run with perseverance the race marked out for us.

Existence is a series of footnotes to a vast obscure unfinished masterpiece.

I was an observer. I liked to listen rather than openly express myself. This trait is something that I've retained over the years.

You better take care of me Lord, if you don't you're gonna have me on your hands.

I will spend the next four years rebuilding the foundation of a opportunity society led by free people and free enterprises.

A dream you dream alone is only a dream. A dream you dream together is reality.

One good thing about TV Land is you're always surrounded by people who know what they're doing, in terms of your fellow actors.

I feel very privileged to have reached so many kids because a life without stories, without the power of books, would be a very grey world, it's good to add colour.

For love is immortality.

The roles... the deep roles that I've gotten to play have turned my course. They've changed my life experience.

Judges wear legal professionalism and precedent as a mantel that secures legitimacy for their decisions. It's how they distinguish themselves from politicians or administrative agencies, while wielding power that is sometimes much greater than those democratically accountable actors.